The invention relates to a method of corrosion protecting steel structural components. More particularly, the invention relates to a method of corrosion protecting motor vehicle structural frames and engine cradles.
Prior to the invention, the corrosion protection of steel components, such as motor vehicle structural frames and engine cradles involved several expensive treatments. As illustrated in FIG. 1, first the component was treated by a steel shot blast mechanical cleaning of the steel structural component to remove scale, rust, and other oxidation residues, and to harden the steel. Then an alkaline wash, a rinse water wash, a phosphate, iron or zinc treatment, and another rinse water wash occurred. Then a non-chrome seal rinse, such as a water soluble polymer rinse, a deionized water rinse, drying, cool down, the application of a relatively thick powder paint film, and the baking of the steel component completed the process. The component was then unloaded and sent on to the customer. The relatively thick powder paint film was required in order to cover the rough surface profile (metal peaks of about 3.5 mil) of the steel left behind by the steel shot. This thick film coating increased the cost of this corrosion method. In addition, the use of the chemical treatments increased cost as well as produced waste disposal problems.